Liquid crystalline polymers (LCPs) are macromolecules possessing significant orientation in either the molten state or in concentrated solution. The state of their solution (lyotropic) or melt (thermotropic) is between the boundaries of solid crystals and isotropic liquids. In the solid state these highly ordered polymers display exceptional strength properties in the direction of orientation. By designing molecules containing only relatively inert chemical bonds, preparation of thermally and oxidatively stable high-performance materials is possible.
A review of thermotropic LCPs can be found in Kwolek et al., "Liquid Crystalline Polymers", "Encyclopedia of Polymer Science and Engineering " 2nd Ed, Vol. 9, pp 23-55 (1987). Among those listed are polyesters. Many liquid crystalline polyesters display several of the desirable attributes of these compounds. Unfortunately, most have too high of a melt temperature for economical melt fabrication.
There is a growing need in the thermoplastic engineering industries to provide for new and improved polyesters and copolyesters which possess a high degree of processability while concurrently exhibiting superior mechanical properties.